Is it possible to dictate a UV map instead of pulling one?
In Edit mode, select the face you want to manually set the UV map for and select Mesh/UV Unwrap.../Reset from them menu (or press U and select Reset). This will reset that face to cover the whole UV space. Then in the UV Editor window (while the face is still selected in the 3D viee) you can manipulate the UV mapping as desired (select the vertices (or A for all) and use G, R, S for Grab, Rotate, Scale, etc